This invention relates to high pressure filter vessels primarily for use in filtering liquids through a bag filter element suspended in the vessel, and more specifically relates to an improved filter vessel which provides distributed liquid flow to the bag filter.
Pressurized liquid filters have become widely employed in industrial filtering operations because high pressure allows continuous, large capacity filtration at high flow rate in relatively compact equipment space. Bag filter elements developed for use in high pressure filtering facilitate difficult separations, such as recovery of carbon black from hydrocarbon pyrolysis effluent, which otherwise require prohibitive time. In continuous service, recurrent replacement of caked filter bags is an important factor in the design of the filter vessel or housing.
In older design of filter bag pressure vessels, the liquid inlet to the filter was fabricated in the housing cover, generally a central port in the cover. Opening the cover to replace filter bag elements generally involved repeated manual disconnection of plumbing couplings between the pressurized liquid supply lines and the cover inlet, as described in U.S. Pat. No. 3,640,392, issued to Smith et al.
In newer design of filter bag pressure vessels, disconnection of plumbing coupling can be eliminated from normal filter bag replacement because the liquid inlet to the filter is formed in the vessel sidewall as described in U.S. Pat. No. 3,814,261 issued to Morgan. This patent proposes a liquid filter having a filter housing for a reticulated basket and a filter bag supported in the basket with the upper margin of the bag making sealing contact with a top fitted over the housing. The top includes an upwardly offset marginal portion which cooperates with a liquid inlet in the housing sidewall to define a passage utilized to direct liquid from the inlet upwardly and over the upper edge of the filter bag and into the bag. A disadvantage in the operation of this structure is that the liquid flow pattern into the filter bag is limited to the portion of the upper edge of the filter bag directly below the corresponding upper offset marginal portion of the top which can also create channeled or localized flow pattern through the filter bag resulting in folded sections of the bag.
The development of the high pressure filter vessel of this invention provides a fluid path distributed over substantially the entire entrance to a restraining basket and filter bag promoting uniform flow through the filter bag and improving the effective filtering surface of the filter bag.